Testing Coils

Well, my bike is buggered. It began backfiring and running rough while riding and I barely made it back home. I shut it off and now there is no spark at all. I'm wondering if my new aftermarket coils fried the CDI thingy. I've no idea where to start looking now.

I just re-read this thread with interest. Didn't realize it started some time ago! Some excellent expert advice with thorough explanations. No argument from me but I'll add my non-technical 2c's worth - in no particular order.
I've had my share of ignition problems, long since resolved. I've had ignition triggers fail. Like the ignition coils, they too can develop an open-circuit and quit working. I simply went to a Bike salvage yard, found a Kawi with the same ignition type (Same triggers) and used this trigger to replace my defective one. Problem solved - years ago ! Then found my 3 ignition-coils were cracked. Did all the reading and research and decided that replacing the coils with new OEM's was not the way to go ( for me). That's when I came upon the suggestion of the G.M. V6 coil-pack. Aware of the controversy regarding coil resistance I decide to KEEP the Ballast resistor and subsequently spent a few hours at an auto-wreckers with meter in hand before I finally found a Pontiac Grand AM that met the required specs. That also was years ago - no more issues. ( And - Time proven!) This is apparently "the Shade-Tree" mechanics way of dealing with these issues but at this juncture, as with so many other "work-a-rounds" that the years have created for this bike - "what ever works, as long as it works". You don't have to be a wizard at electronics to do this work but this is where I will agree - You simply can't bolt on any part that "looks" like it might work or YES - you risk frying stuff. I went in with some knowledge, explored the topic in depth and made an informed decision - successfully.
Again - not being argumentative to the experts opinions. In the end you must do (intelligently) what you must do to accomplish the task. My conversion was not "Luck". Resting purely on "Luck" is foolish and expensive.
Regarding the ballast resistor. Every time the topic of coils/ ballast resistors comes up there is ALWAYS the same comment: "If the Ballast-Resistor fails, you'll burn out the ignition unit". This has never made any sense to me and I'm calling B./S. The OEM ballast resistor has one power lead feeding it. There are 3 separate resistors in the ceramic block. I'll guess 3 Ni-Chrome resistor winding's that terminate with one output per ignition-coil. Embedded in ceramic there is only one type of failure that can occur. The resistance winding(s) can over heat and "open". In essence - melt like a fuse. Internally speaking they can not "short-circuit" They're embedded in ceramic ! The B/R will either conduct or not conduct. If it fails it can only fail one way ! No power to that coil. No smoke, no fire, no catastrophic ignition module failure. No power - No power damage. However I will agree: If after-market coils are not carefully selected AND if used and mismatched to the ballast-resistor ( if used) , then your setting yourself up for failure and disappointment and more $$$$$ because of the explanations in this thread. "Mismatching coils (with or with out the B/R) will end in disaster".
The odds of all three resistors in the Ballast-resistor block failing simultaneously in my mind is non-existent unless some how the power to the B/R is adversely high. The only way this could happen(?) is if the voltage regulator fails and the charge voltage is uncontrolled/unlimited. Then you'll "fry" everything. Coils and resistors will then be the least of your concerns.
On another topic of sorts but still related, I'll share my most recent experience with a "WTF" moment. I recently replaced the OEM fuse block with a 6 output "blade" type fuse box. Why is not important ! On a recent ride the bike started missing. Not just one or two cylinders but ALL of them. Just for a split second but enough times to make me turn for home. I immediately knew it was an ignition problem. First thing I checked was the Battery voltage, having just replaced my stator and voltage regulator. Good battery, so good charging! Next: power coming into the Ballast-resistor?. Power in checked OK. Continuity and Power out X3 - OK. (Cleaned up the otherwise clean terminals and tightened the females for good measure.) I moved on the the Bullet-connectors from the B/R (PINK) to the coils. All OK.
Then checked the connectors at the ignition module. All OK. This now became an example of needing to "think outside the box." Because most everything "powered" comes from the ignition-switch I decided to check the 30amp circuit. The starting point was at the fuse and this is where I found the source of the ignition failure. The 30amp MAIN blade-fuse plastic body was partially melted! This meant one thing to me. Resistance/Heat. Inspecting the fuse showed some arching. Long story short - Not all fuses are created equal. A "Google" search (after the fact) provided this info. The blade type fuse box came with fuses. They turned out to be CRAP. I replaced them with some from an Auto-supplier and discovered that the thickness of the blades on the "cheap supplied fuses was measurably thinner then the "better" ones. The "Cheap ones" also had a "coating" that could be rubbed off (?) New fuses - Problem solved.
In keeping with the "Shade-tree" mechanic comment, one could state that I got what I deserved by changing out the fuse box style! Not the point ! Clearly, my bike is not that of a purist. Few are. What's important to keep in mind is that after 38 years things are going to fail and need replacing. If OEM parts are available, we must assess whether the replacement parts are going to be reliable or whether we need to "upgrade" for that reliability. Coils are a good example. No one replaces OEM coils with OEM coils ( even if available) We know they're inferior and will fail. There is certainly no argument that "What coils to use?" is controversial. And I again agree - Attempting to keep the parameters in line with what was originally designed is always best.......But there's a point where common-sense and practicability MUST enter the equation. And the key word is "Common-sense". If you don't do the background research and make informed and logical decisions and determinations, alternative options will likely fail and possibly cascade.
"Slapping it on and seeing if it works" is not the way to accomplish repairs, I agree. Whether in the form of Lauri's Ignition-modules ( Complex and technical) , Brass Floats ( not so much but equally critical), new MOSFET V/R's or ignition-coils....... if not for the educated, rational and logical attempts to resolve issues by some......... most of these machines would be in the form of cutlery and pots and pans in our kitchens !
The Bottom_line is simple: If a modification has been successful for a lengthy period of time and has PROVEN itself to perform AND be reliable then you must decide whether you'll accept it as an alternative, blow it off because "the #'s don't quite match" or whether you're going to be riding - at all !
If this rambling spawns an idea - Great ! That was the point. If you don't agree - That's great ! Everyone has their own philosophies. The question remains: You're riding - or you"re not ! As pointed out: This hobby may not be for everyone !

Wow very informative. But how does one check the CDI unit to see if it's failed? I don't live near a bike salvage yard and really can't afford to buy an aftermarket on spec.

how does one check the CDI unit


The Manual tells you how.

I actually have the manual on a CD and had a look. IC Igniter, right? It does explain how to check the unit
so I'll give it a shot. I'm afraid I'm mechanically challenged when it comes to this stuff. I believe I downloaded the manual from this site about 10 years ago. If anyone wants a copy I can see if I can upload it.

Just following this topic as at one point I will be checking these components before installing them. My original coils look good, except rust on the posts and protective rubber components broken. I would probably try to install these coils after cleaning but I'd like to get a set of new NGK ignition boots and the cables.
Ok, since I am already talking. Could anyone point me to the source of the right boots and cables?